Conventionally, when a concrete paving operation is accomplished, a vibrator is employed for providing a vibration to the cement in order to smooth the cement through the site field to pack or tighten it. The present invention improves this process by selecting the vibration speed in accordance with the characteristics of the cement and slab particle sizes.
In accordance with the present invention, for example, a vibration speed of 1,500 vpm (vibrations per minute) and 9,000 vpm, for rough particle slab structures and for cement and finely divided particle structures, respectively, may be used. This vibration method eliminates any air gap or gaps in the concrete cement interior, and provides increased strength and esthetic beauty for the finished concrete cement.
Known conventional vibrators use a given balance weight attached about a rotary shaft of a motor with the motor driven in a given rotary direction, thus establishing a single given speed, force and bandwidth (or time period) of the vibration. With a unitary vibration, as is used in the prior art, sands and stones comprising the concrete cement become separated in accordance with the weight of the various particles.
Known vibrators frequently insert a rod type vibration member into the concrete cement, but recent building requirements dictate anti-vibration construction techniques which utilize a high distribution of iron rod members in the concrete. This makes it difficult to insert the rod vibrator member into the concrete as required by the conventional vibrators.
Furthermore, pouring and curing of concrete is a time-critical process. Hence, the concrete should be quickly poured with a concrete mixer pump vehicle. Thus, many workers are required for pouring and curing jobs, thereby requiring much manpower to operate numerous vibrators.
Known vibrators are usually heavy in weight yet supported by a wooden frame. Consequently, failure of the wooden frames is a common problem.
To overcome at least these cited drawbacks of the prior art, in addition to others, this invention provides a method and apparatus for curing concrete cement with continuous paving from pouring to curing, by giving suitable vibrations at suitable times, all within a short time period.